Low-Power, 12-Bit Sampling ADCs with Internal Reference and Power-Down

The MAX190/MAX191 are monolithic, CMOS, 12-bit ana­log-to-digital converters (ADCs) featuring differential in­puts, track/hold (T/H), internal voltage reference, internal or external clock, and parallel or serial µP interface. Both devices have a 7.5µs conversion time. The MAX190 has a 5µs acquisition time and sampling rate of 76k samples per second (ksps), while the MAX191 has a 2µs acquisi­tion time and is guaranteed at 100ksps.

Decoupling capacitors are the only external components needed for the power supply and reference. These ADCs operate with either an external reference, or an internal reference that features an adjustment input for trimming system gain errors.

Both the MAX190 and MAX191 operate from a single +5V supply. The MAX191 also operates from dual ±5V sup­plies, allowing ground-referenced bipolar input signals. Both devices feature a logic power-down input, which reduces the 3mA Voo supply current to 50µA max, includ­ing the internal-reference current.

The MAX190/MAX191 provide three interface modes: two 8-bit parallel modes, and a serial interface mode that is compatible with SPI, QSPI and Microwire™ serial-inter­face standards.

APPLICATIONS

* Battery-Powered Data Logging

* PC Pen Digitizers

* High-Accuracy Process Control

* Electromechanical Systems

* Data-Acquisition Boards for PCs

* Automatic Testing Systems

* Telecommunications

* Digital-Signal Processing (DSP)

* 12-Blt Resolution, 1/2LSB Linearity

* +SV or ±SV Operation (MAX191)

* Built-In Track/Hold

* Internal Reference with Adjustment Capability

* Low Power:

* 3mA Operating Mode

* 20µA Power-Down Mode

* 100ksps Tested Sampling Rate (MAX191)

* Serial and 8-Bit Parallel µP Interface

* 24-Pln Narrow DIP and Wide SO Packages